Kim Philby, the so-called Third Man in the Cambridge spy ring, was the Cold War's most infamous traitor, a Soviet spy at the heart of British intelligence. Philby joined Britain's secret service MI6 during the war and went on to head the section tasked with rooting out Russian spies before becoming the service's chief liaison officer with the CIA. He betrayed hundreds of British and US agents to the Russians and compromised numerous operations inside the Soviet Union. Tim Milne was Philby's closest and oldest friend. They studied at Westminster School together and when Philby joined MI6 he immediately recruited Milne as his deputy. Philby's treachery was a huge blow to Milne and, after he retired, he wrote a highly revealing description of Philby's time in the secret service. Publication of the memoirs was banned by MI6 but, after Milne's death in 2010, his family were determined that this insider's account of the Philby affair be published. Edited to include newly released top-secret documents showing how the KGB's 'master spy' managed to fool MI6 even after he defected to Moscow, this is the final word on one of the world's most notorious spies by the MI6 colleague who knew him best, the insider account of the Philby affair that Britain's spy chiefs did not want you to read.

Ian Innes 'Tim' Milne CMG OBE, nephew of A. A. Milne, was born in Brentford in 1912. He won a King's Scholarship to Westminster School and then read Classics at Christ Church, Oxford. In 1934, he became a copywriter with the advertising agency S. H. Benson, working on a number of accounts, including Guinness, Kodak, Bovril and Colman's mustard. He was commissioned into the Royal Engineers in 1940 and in October 1941 recruited into MI6 by his childhood friend Kim Philby. Milne continued to work in MI6 until 1968, serving in Iran, Germany, Switzerland, Japan and Hong Kong. After leaving MI6, he became a senior clerk in the House of Commons. He retired in 1978 and subsequently wrote these memoirs but, due to an MI6 ban on the book, he never saw them published. Milne died in 2010.